This invention relates to electrical appliance control and particularly concerns a transmitter or controller for the remote control of slave units.
U.K. Pat. No. 1592971 discloses a remote control system for electrical appliances. That system comprises a power main having a plurality of power outlets, at least one slave unit having a power input coupled to the main and operable to control the supply of power to an appliance, and a transmitter for controlling the or each slave unit, the transmitter comprising: means for generating selectively digital instruction signals at least some of which contain an address of a slave unit; and means for modulating said digital signal onto the power main, and the or each slave unit comprising: means for defining the address of that unit; means for receiving the digital signal from the main and means for responding to that signal when the address of the defining means and any address contained in the digital signal have a predetermined correspondence.
Such a system will hereinafter be referred to as a "system as herein defined".
Preferably the address in such a system includes an area code or address defining an area, building or home in which the system is to operate.
In one practical form, the system has various types of transmitters such as command consoles, timers and computer interfaces all of which are designed to transmit a digitally encoded 120 KHz signal onto a domestic or other power line. This signal is received by various types of slave units (receivers) such as lamp dimmers, wall switch dimmers and appliance modules which can then turn on or off appliances and dim or brighten lamps upon receipt of the appropriate code from a transmitter. All types of transmitters send the same code format so that a receiver will respond to codes from any type of transmitter in the system. A control system for a vehicle is disclosed in U.K. specification No. 1607816 (Belgian Specification No. 874722) and which uses digital control signals containing addresses. However, the power supply and signal path are distinct, although in one cable, so this system is not applicable directly to a domestic control system as disclosed in U.K. Specification No. 1592971. Each transmitter is preset to communicate only with selected local processing units.
An object of the present invention is to provide a transmitter (or controller) which can be designed for controlling the same types of receiver as do the transmitters described in the above-mentioned Patent and which has improved facilities.